A light-emitting apparatus is widely used for homes, in industry, and in vehicles. For example, a halogen lamp, a high-intensity discharge (HID) lamp, a xenon lamp, and a light-emitting diode (LED) are used as a light source of a light-emitting apparatus that is mounted in a head lamp for vehicles. In addition, increasing attention is being paid to a laser diode (LD) as a next-generation light source of the light-emitting apparatus. In the case in which the LD is used for vehicles, it is possible to satisfy functional requirements, such as long-distance radiation and searchlight function, design, and efficiency. The reason for this is that the LD exhibits higher luminance than conventional light sources and occupies a smaller area than the conventional light sources and that the LD exhibits unique characteristics such as straightness and polarization. Consequently, it is expected that the LD will attract much more attention than conventional light sources in the future.
For example, a light-emitting apparatus may be applied to an illumination apparatus that is mounted to a front portion of a vehicle, for example, a day running light (DRL). The DRL is used for the purpose of reducing the incidence of traffic accidents. That is, the DRL enables pedestrians to perceive the location or presence of a traveling vehicle when the weather is rainy or dark in the daytime, thereby protecting pedestrians from collisions with the vehicle.
DRLs may be individually mounted on a front left side and a front right side of a vehicle and may be required to radiate white light. In most cases, a light-emitting diode (LED) is used for a DRL for vehicles. There is also demand for an organic light-emitting diode (OLED) as a light source of a DRL. However, an OLED is not commonly used for a DRL due to lack of reliability. A DRL also acts as a powerful means of expressing the identity of a vehicle brand.
Since a conventional light-emitting apparatus for use in a DRL employs an LED, it has a complicated structure in order to be adapted for the design of a vehicle. The reason for this is that an illumination apparatus for vehicles, specifically, an illumination apparatus used as a DRL, has a curved design rather than a straight design. Further, a conventional illumination apparatus used as a DRL has a relatively large volume because the area occupied by parts for driving a light source and the area occupied by parts for dissipating heat are relatively large.